The development of an efficient and sustainable transportation system is crucial for the effective functioning of economies. Concrete, a widely used material for road construction, poses significant environmental challenges. A sustainable alternative is to use alkali-activated concrete (AAC) for road construction. However, the aggregates used in AAC are generally mined, contributing to the negative environmental impact. To address this concern, municipal solid waste incineration (MSWI) ashes, specifically MSWI bottom ash (BA), can be utilised to replace natural aggregates. Thus the construction of pavements using sustainable concrete facilitates its growing demand without burdening the environment.

This research focuses on the utilisation of municipal solid waste incineration bottom ash (MSWI BA) aggregates in AAC for potential application in pavements. The study was divided into five phases: aggregate characterisation, mechanical performance evaluation, long-term performance study, microstructure analysis, and life cycle assessment (LCA) analysis. The physical properties of MSWI BA aggregates indicated that the aggregates are porous and weak. Nonetheless, these aggregates showed comparable properties to natural aggregates and can still be used for pavement application. However, the metallic aluminium in the MSWI BA aggregates releases hydrogen gas leading to concrete cracking and swelling, thus, hindering its use in various applications. To address this concern, alkaline pre-treatment using sodium hydroxide solution was employed in this research. An optimal replacement level of 30% was chosen based on the effectiveness of the pre-treatment in removing metallic aluminium and the compressive strength of AAC containing MSWI BA aggregates.

In the next phase of the research, the mechanical and long-term performance of AAC with optimum replacement level was evaluated. The results demonstrated that the concrete satisfied the mechanical performance requirements for pavements. However, the freeze-thaw resistance of the AAC was below the norm requirement due to the air voids and associated cracking, which was confirmed through scanning electron microscopy (SEM) and X-ray computed tomography analysis.

SEM analysis revealed reactive phases in the MSWI BA aggregates and poor aggregate-matrix bonding for the coarser fraction compared to the finer aggregate fraction, leading to decreased mechanical performance. Despite these findings, the AAC containing MSWI BA aggregates satisfied the majority of the norm requirements, indicating its potential for road pavement application. However, evaluating the environmental impact of adding MSWI BA aggregates in concrete is essential. The life cycle assessment analysis demonstrated that the optimal MSWI BA sample exhibited better environmental effects, indicated by a lower environmental cost indicator value compared to AAC and ordinary Portland cement concrete samples with similar performance.

In conclusion, the pre-treatment method utilised in this research is optimal for a replacement level of 30% of gravel with MSWI BA aggregates. The AAC with 30% replacement level meets all the mechanical property requirements stipulated by the norm for pavement application, exhibits good air void distribution, and has limited environmental impact owing to the lower ECI value. This study evaluated the feasibility of applying MSWI BA aggregates in AAC for pavement application and showed promising results.

This dissertation endeavors to introduce a novel supervised Structural Health Monitoring (SHM) methodology for the detection of damage and the prediction of fatigue life in asphalt concrete materials. Grounded in the principles of S-N (strain-number of cycles until failure) curves, this research addresses the intricate task of proficiently monitoring asphalt pavements through the utilization of sensor data, thus optimizing maintenance schedules. The successful implementation of this methodology holds the promise of significant cost savings, primarily by facilitating timely inspections and judicious resource allocation. The comprehensive approach encompasses an extensive literature review, encompassing topics such as asphalt properties, fatigue life, and damage prediction models. It also involves the strategic deployment of piezoelectric sensors, with a specific emphasis on Lead Zirconate Titanate (PZT), as well as four-point bending (4PB) testing. This methodology is further enriched by the incorporation of supervised machine learning techniques for the precise prediction of strain levels, subsequently utilized in fatigue life prediction and damage modeling.

Turnouts allow trains to change from one track to another. Therefore, they are an essential part of infrastructure to create and operate a railway network. This project focuses on the (common) crossing; the part of the turnout where the inner rails cross through one another. Because of the shape of the wheels, it is necessary to create a discontinuity in the rail at this location. As a consequence, wheels experience a disturbed support which causes wear, deformation and fatigue on the crossing. In the Netherlands, this problem has a high priority. This is because the Dutch railway network is unique in two ways; it is very dense and it has a high utilisation. Per km2 of land area, the Netherlands has the second highest amount of track length (right after Switzerland). Per km of track, the Netherlands has the second highest amount of passenger kilometres (right after Japan). The consequence is a set of 7000 that are relatively heavy loaded.
In order to extend the lifetime of these crossings, they have to be monitored and maintained. In present practise, some deformations have to be cut off and cracks have to be ground away. This ensures safe wheel passages and prevents fatigue related failures. Such practises are described well, within the current norms.
A less clear topic however, is the maintenance of geometry. Geometry is defined as the cross-sectional shape of the rail. As soon as the geometry of a crossing changes due to deformation and wear, the vehicle behaviour is influenced. Unfavourable geometry can lead to a big amplification of dynamic forces from passing wheelsets. For this reason, maintainers seek for favourable ways to assess and control the shape of worn/deformed crossings.

The crumb rubber modified bitumen (CRMB) has been utilized in pavement industries to mainly reduce the environmental impacts of the wasted tires by turning unwanted scrap tires into new bituminous materials. However, the relatively high viscosity compared to the conventional asphalt is the major drawback of the CRMB. The higher mixing and working temperatures are thus required in order to achieve the desired workability of the CRMB. This results in more asphalt fume emission, higher energy consumption, and more harmful working environments for workers. Warm mix asphalt (WMA) technologies have been intentionally developed to lower the manufacturing and working temperatures of the asphalt by reducing the viscosity of the asphalt binder. Many studies suggested that coupling CRMB with WMA additives can promote better working conditions and minimize environmental issues of the CRMB.
In this study, experimental works were carried out to evaluate rheological and performance-based properties of the CRMB containing WMA additives in order to investigate the effect of the crumb rubber modifier (CRM) content and WMA additives (wax-based and chemical-base WMA additives) by using only one dynamic shear rheometer (DSR). The performance of the studied binder at high, intermediate, and low road service temperatures were investigated by performing Multiple Stress Creep and Recovery test, Linear Amplitude Sweep test, and 4-mm Dynamic shear rheometer test, respectively. Moreover, the Fourier Transform-Infrared Spectroscopy and the storage stability test were also performed to investigate the effects of the CRM dosage and the WMA additives on the aging susceptibility and the high-temperature storage stability of the binders. The results show that the incorporation of crumb rubber modifier can clearly improve the overall performance (rutting, fatigue damage, low-temperature thermal cracking resistances), and aging resistance of the asphalt binder in a bitumen-level. The high-temperature storage stability of the CRMB became more stable at the higher dosage of the CRM. Moreover, it was found that the wax-based WMA additive can only enhance the high-temperature rutting resistance but negatively impacted the fatigue and low-temperature damage resistances of both neat and CRM binders. The effect of the chemical-based additive on the neat and CRM binders are different as it improved the performance over the whole service temperature of the neat but lowered the damage resistances of CRMBs. Additionally, the addition of both WMA additives decreased the high-temperature storage stability of the CRMB.

The term peat is commonly used to describe organic soils, composed of fragmented plant remains and fibers. Despite the extensive research on the behaviour of peat during the last 50 years, the vast majority of the attention was devoted to the volumetric behaviour. Only few attempts are reported to model the deviatoric behavior of peat, which is fundamental in many geotechnical applications as dykes founded on peat layers. This Thesis represents an attempt to understand the current knowledge on the deviatoric behaviour of peat with the aid of an hierarchical simple elasto-plastic model.

The constitutive model was conceptually developed aiming for the use of a limited number of parameters with an easy way of determination. This choice aligns with the needs of engineering practice, which demands the use of models with few and comprehensive parameters. The constitutive ingredients of the model have been derived from direct experimental evidences. The model requires 10 parameters, 5 out of them are the classical parameters of the well-known Modified Cam-clay model.\\
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The high compressibility of the peat along with its high friction angle intensify the end restraints occurring due to the platens of triaxial apparatus. In order to account for the effects of the boundaries, the constitutive model has been implemented in the Finite Element Programme LAGAMINE and the tests have been simulated as Boundary Value Problems. The model is in qualitative agreement with the experimental data and, in particular, with quantitative agreement until 20\% of strain for the case of consolidated drained triaxial tests. To be able to reproduce properly the case of consolidated undrained triaxial tests which impose an isochoric response, one parameter associated with the flow rule of the model should be changed. This change of a parameter is related to the fact that the fibers in the peat specimen are not considered explicitly in the constitutive equations, although they can alter the deformational response of peat under some kinematic constraints and influence the mechanical response in a predominant way at high strain levels.

Overall, the constitutive model developed in this Thesis gives good quantitative results until 20\% of axial strain. Further research on the influence of fibers on the response of peat under different strain paths and on the consequent matrix-fiber interaction should be done in order to have a model with predictive capabilities until high strain levels.